Anything is possible, but that is the major structural member of the car that is rusted out. It's going to require considerable time and patience to fabricate new frame rails, and seal everything up. Not to mention the fact that I'm sure this is just the tip of the iceberg (maybe it's the worst of it, but I bet there's a lot more). Looks like the rocker is gone.
If you're doing it yourself, looking for a project to fill up your free time, knock yourself out.
If you're paying someone to do it. It'd be far cheaper to have a solid shell shipped to you from another part of the country.